[AVRO-966] Bug in GenericData#resolveUnion when resolving union of null and array

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 1.6.1
• Fix Version/s: 1.6.2
• Component/s: java
• Assignee: Doug Cutting
• Reporter: Vyacheslav Zholudev
• Created: 30/Nov/11 13:26
• Updated: 15/Feb/12 00:46
• Resolved: 07/Dec/11 23:16

Description

I have a simple avro schema from which I generate an avro specific object:
{{
{"type": "record",
"name": "org.company.Test",
"fields": [
{ "name": "arr","type": ["null",

{"type": "array","items": "float" }

], "default": null }
]
}
}}
Then a simple piece of code to reproduce a bug:
{{
Test test = new Test();
List<Float> list = new ArrayList<Float>();
list.add(1.1f);
list.add(2.2f);
test.setArr(list);

DataFileWriter<Test> myWriter = new DataFileWriter<Test>(new ReflectDatumWriter(test.getSchema()));
File f = new File("/tmp/test.avro");
myWriter.create(test.getSchema(), f);
myWriter.append(test);
myWriter.close();
}}

I get an exception:
{{
Exception in thread "main" org.apache.avro.file.DataFileWriter$AppendWriteException: org.apache.avro.UnresolvedUnionException: Not in union ["null",

{"type":"array","items":"float"}

]: [1.1, 2.2]
at org.apache.avro.file.DataFileWriter.append(DataFileWriter.java:261)
<my code>
Caused by: org.apache.avro.UnresolvedUnionException: Not in union ["null",

{"type":"array","items":"float"}

]: [1.1, 2.2]
at org.apache.avro.generic.GenericData.resolveUnion(GenericData.java:549)
at org.apache.avro.generic.GenericDatumWriter.resolveUnion(GenericDatumWriter.java:137)
at org.apache.avro.generic.GenericDatumWriter.write(GenericDatumWriter.java:70)
at org.apache.avro.reflect.ReflectDatumWriter.write(ReflectDatumWriter.java:102)
at org.apache.avro.generic.GenericDatumWriter.writeRecord(GenericDatumWriter.java:105)
at org.apache.avro.generic.GenericDatumWriter.write(GenericDatumWriter.java:65)
at org.apache.avro.reflect.ReflectDatumWriter.write(ReflectDatumWriter.java:102)
at org.apache.avro.generic.GenericDatumWriter.write(GenericDatumWriter.java:57)
at org.apache.avro.file.DataFileWriter.append(DataFileWriter.java:255)
}}

My investigation showed that in GenericData#resolveUnion method getSchemaName() is called. And the latter method when checks whether datum is a record, succeeds. Why it happens boils down to the fact that in ReflectData#createSchema an "if"-body under case (type instanceof ParameterizedType) is not executed.

I can supply more details if needed. Or explain in a clear way if I didn't manage to.